Thanks for your thoughts Elaida.
 I think it is really hard at this age to know whether it is speech delay or he is a late talker but what I have read suggests that not having 1-2 words by 12 months and 5 words (not inc mumma and dadda) by 18 months is a 'red flag'. I thought at one stage the delay might be due to holding back because of the signs but I am not so sure any more. He is a very vocal child, and I can tell he is trying to say things, but he just says the same thing for almost every word he tries  'dat'  or 'be' (depending on which more closely resembles the word!). Having said that, he has just learnt 'mumma' and is taking obvious delight in saying it! He doesn't babble with a very large range of sounds, so I think what is holding him back is producing the speech sounds.
It may all come together in a couple of months but I'd prefer to be on the safe side particularly considering the hearing loss. Language is so important!
It's interesting what you said about your son. Strange how some kids can pick up language despite hearing difficulties etc. Maybe your son is really bright!? I've done all the reading animal books and making animal sounds but the most I have got back is 'dat' for quack! Oh well. I don't think my son particularly language orientated in the first place Its all about go go go and do do do.
I'll  check out 'The Talking Baby' on google.

I've got a super active little toddler (17months) who started walking etc early and is not particularly interested in screen time either. My situation is fairly different (only just started teaching reading, he is younger & he is delayed in spoken language too due to hearing problems) but I've been experimenting with a couple of things that factor in his activity level and seem to be working. I only play little reader in short 2-3 minutes bursts, and sometimes swing him up and down etc with the cadence of the language. A couple of days ago I put sticky labels on the fridge with his favorite foods written on them and have been getting him to point to them  and see what food I bring out (this one is proving a real success). He is in the very early stages, and I am not expecting great things, but at least he is beginning to show an interest in print (pointed some writing out to me the other day).

It sounds too like he might have begun to actively resist reading? I like Mom2bee's idea of finding his 'passion' and introducing reading again indirectly through his interest.

And it is amazing what children learn 'latently'. I keep on thinking of a post I read the other day where a mum said she  gave up teaching sign language to her baby at 7 months because she didn't see any progress. Then 5 months later, after no signing during this period, her son suddenly signed 'fish'.

Hi Aaron, that would be great. I sent you my email in a private message ;-)

Thank you for your advice. I think I was suddenly hoping he would start speaking after the grommets were put in - perhaps a little too much to ask after at least 8 months of poor hearing!
I like your idea about getting another child to demonstrate the speaking of the words on Little Reader. He is very curious about other children and likes to copy. Now to find that other child!

I am a little concerned about my 16 month old. He is not saying anything accept 'nana' for bananna and 'be' for 'bell'. He doesn't even say 'mamma' or 'dadda'. I am not concerned about autism as he is babbling a lot, communicates with pointing and around 40 baby signs & is very social. In all other areas he is on track. His verbal comprehension appears to be ok - he can understand simple instructions like 'Bring mummy the book'. He is a very physical child & was walking, climbing, feeding himself, drawing etc earlier than average.
I discovered a couple of months ago that his hearing was probably being effected by fluid in the ears& recurrent ear infections. The tester, however, had difficulty determining the exact extent of hearing loss because he wasn't particularly interested in the testing task. She said the hearing loss could have been anything from 'mild' to 'considerable'. He had grommets to drain the fluid in ears put in about two weeks ago. I think I have noticed a difference in his verbal comprehension since but it is difficult to tell.
Should I be worried that he is not speaking yet or is it too early? Is there anything else I can do to assist his speech development? I am using Little Reader so I am hoping that that will help his verbal comprehension (if not give him a head start in reading!).I am also trying to articulate things more clearly when speaking to him but apart from that I am at a loss.